1. Field of the Invention
This invention relates to a rope-operated actuator, more particularly to a rope-operated actuator for an engine starter of a lawn mower.
2. Description of the Related Art
FIGS. 1 to 5 illustrate a conventional rope-operated actuator for an engine starter 2 of a lawn mower 1. The conventional rope-operated actuator includes: a cover 11 formed with a central shaft 113; a spool wheel 12 mounted coaxially and rotatably on the central shaft 113; a spiral spring 122 disposed between the cover 11 and the spool wheel 12 and, having two opposite ends that are respectively secured to the cover 11 and the spool wheel 12; a rope 123 connected to the spool wheel 12 for driving the spool wheel 12 and extending through a hole 112 in the cover 11, the rope 123 being rewindable around the spool wheel 12 through the spiral spring 122, and being provided with a handle 14; a pawl-driving disc 13 disposed at one side of the spool wheel 12 opposite to the cover 11 and formed with two opposite guiding grooves 136; a pair of diametrically disposed pawls 131 disposed between the spool wheel 12 and the pawl-driving disc 13, pivoted to the spool wheel 12, co-rotatable with the spool wheel 12, and pivotable relative to the spool wheel 12 between engaging and disengaging positions, each of the pawls 131 extending in a radial direction relative to the spool wheel 12, and being formed with a stud 135 that extends in the axial direction into a respective one of the guiding grooves 136 (see FIG. 4) so as to permit the pawls 131 to be driven by the pawl-driving disc 13 to pivot relative to the spool wheel 12 from the disengaging position to the engaging position when the spool wheel 12 is rotated together with the pawls 131 in a first rotational direction, and from the engaging position to the disengaging position when the spool wheel 12 is rotated together with the pawls 131 in a second rotational direction opposite to the first rotational direction; a pair of diametrically disposed coil springs 133, each of which is disposed between the spool wheel 12 and a respective one of the pawls 131 and each of which urges the respective one of the pawls 131 to abut against the pawl-driving disc 13; and a screw rod 134 extending through the pawl-driving disc 13 to engage threadedly the central shaft 113 for retaining the pawl-driving disc 13 thereon and for retaining the spool wheel 12 on the central shaft 113. The pawls 131 engage releasably a flywheel 21 of the engine starter 2 when the pawls 131 are moved to the engaging position upon pulling of the rope 123, thereby permitting co-rotation of the fly wheel 21 and the spool wheel 12. The cover 11 is further formed with a spring-securing part 115 that is disposed adjacent to the central shaft 113 for retaining one end of the spiral spring 122. The spool wheel 12 has a ring that is formed with a spring-retaining recess 124 (see FIG. 3) for retaining the other end of the spiral spring 122.
The conventional rope-operated actuator is disadvantageous in that since the pawl-driving disc 13, which abuts against the pawls 131 through the urging action of the coil springs 133, is only sleeved around the screw rod 134, the pawl-driving disc 13 tends to wobble due to the urging action of the coil springs 133 during rotation of the spool wheel 12, which can result in undesired movement of the studs 135 of the pawls 131 to the outside of the guiding grooves 136, which, in turn, results in movement of the pawls 131 to an undesired position. As a consequence, the engine starter 2 may be unable to function smoothly. In addition, mounting of the coil springs 133 between the spool wheel 12 and the pawls 131 is relatively inconvenient and difficult, which can result in an increase in manufacturing costs. Moreover, the spiral spring 122 is required to be deformed and reduced in size prior to installation between the cover 11 and the spool wheel 12, which is laborious and inconvenient during assembly. Furthermore, the position of the rope 123 tends to deviate from a tangential direction relative to the spool wheel 12 (see FIG. 5) during a pulling operation, which can result in wearing of the rope 123 and cause difficulty in pulling the rope 123.